Ophthalmic surgical microscope having an OCT-system

ABSTRACT

An ophthalmic surgical microscope ( 100 ) has a microscope main objective ( 101 ) and a viewing beam path ( 105 ) which passes through the microscope main objective ( 101 ) for visualizing an object region. The ophthalmic surgical microscope ( 100 ) includes an OCT-system ( 140 ) for recording images of the object region ( 108 ). The OCT-system ( 140 ) includes an OCT-scanning beam ( 142 ) which is guided via a scan mirror arrangement ( 146 ) to the object region ( 108 ). An optic element ( 147 ) is provided between the scan mirror arrangement ( 146 ) and the microscope main objective ( 101 ). This optic element ( 147 ) bundles the OCT-scanning radiation exiting from the scan mirror arrangement ( 146 ) and transfers the same into a beam path which passes through the microscope main objective ( 101 ). Alternatively or in addition, the ophthalmic surgical microscope ( 100 ) includes an ophthalmoscopic magnifier lens ( 132 ) which can be pivoted into and out of the viewing beam path ( 105 ) and the OCT-scanning beam path ( 142 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of German patent application nos. 102006 052 513.2 and 10 2007 019 680.8, filed Nov. 6, 2006 and Apr. 24,2007, respectively, the entire contents of which are incorporated hereinby reference.

FIELD OF THE INVENTION

The invention relates to an ophthalmic surgical microscope having amicroscope main objective and a viewing beam path which passes throughthe microscope main objective. The ophthalmic surgical microscopefurther includes an OCT-system for recording images of an object region.The OCT-system includes an OCT-scanning beam which is guided via a scanmirror unit to the object region.

BACKGROUND OF THE INVENTION

A surgical microscope of the kind referred to above is known from U.S.Pat. No. 6,004,314. This surgical microscope includes an OCT-systemwhich generates a scanning beam of short coherent laser radiation. TheOCT-system includes an analyzer unit for evaluating interferencesignals. The OCT-system further includes a device having two scanmirrors for scanning the OCT-scanning beam. These scan mirrors can bedisplaced about two axes of movement. The OCT-scanning beam in thesurgical microscope is coupled via a divider mirror into theilluminating beam path of the surgical microscope. The OCT-scanning beamis deflected with the illuminating beam through the microscope mainobjective to the object region.

Via optical coherence tomography, an OCT-system makes possible thenon-invasive display and measurement of structures within a tissue. Asan optical image producing method, the optical coherence tomographyespecially generates section and volume images of biological tissue witha micrometer resolution. A corresponding OCT-system includes a sourcefor time-dependent incoherent and spatially coherent light having aspecific coherence length which is guided to a specimen beam path and areference beam path. The specimen beam path is directed to the tissue tobe examined. Laser radiation, which is backscattered into the specimenbeam path because of scatter centers in the tissue, superposes theOCT-system with laser radiation from the reference beam path. Aninterference signal results because of the superposition. The positionsof the scattering centers for the laser radiation in the examined tissueare determined from this interference signal.

For OCT-systems, the building principles of the “time-domain OCT” and ofthe “Fourier-domain OCT” are known.

The configuration of a “time-domain OCT” is described, for example, inU.S. Pat. No. 5,321,501 with reference to FIG. 1a at column 5, line 40,to column 11, line 10. In a system of this kind, the optical path lengthof the reference beam path is continuously varied via a rapidly movingreference mirror. The light from specimen beam path and reference beampath is superposed on a photo detector. When the optical path lengths ofthe specimen and reference beam paths are coincident, an interferencesignal is provided on the photo detector.

A “Fourier-domain OCT” is, for example, described in internationalpatent publication WO 2006/100544 A1. To measure the optical path lengthof a specimen beam path, light from the specimen beam path is superposedonto light from a reference beam path. In contrast to the time-domainOCT, the light from the specimen beam path and reference beam path isnot supplied directly to a detector for a measurement of the opticalpath length of the specimen beam path but is first spectrally dispersedby means of a spectrometer. The spectral intensity of the superposedsignal generated in this manner from specimen beam path and referencebeam path is then detected by a detector. By evaluating the detectorsignal, the optical path length of the specimen beam path can bedetermined.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a compactly configuredophthalmic surgical microscope which permits the recordation ofOCT-section images of the human eye. Here, the OCT-scanning beam can beguided to an OCT-scanning plane without intensity losses.

The ophthalmic surgical microscope of the invention is for defining aviewing beam path and includes: a microscope main objective mounted soas to permit the viewing beam path to pass therethrough permittingexamination of a region of an object; an OCT-system for recording imagesof the object region; the OCT-system providing an OCT-scanning beam andincluding a scanning mirror device for scanning the OCT-scanning beam;and, an optical unit mounted between the scanning mirror device and themicroscope main objective for bundling the OCT-scanning beam exitingfrom the scanning mirror device and guiding the bundled OCT-scanningbeam into a beam path passing through the microscope main objective tothe object region.

In another embodiment of the invention, the ophthalmic surgicalmicroscope is for defining a viewing beam path and includes: amicroscope main objective mounted so as to permit the viewing beam pathto pass therethrough permitting examination of a region of an object; anOCT-system for recording images of the object region; the OCT-systemproviding an OCT-scanning beam and including a scanning mirror devicefor scanning the OCT-scanning beam; an ophthalmoscopic magnifier lensbeing movably mounted; the ophthalmoscopic magnifier lens being movablebetween a first position whereat the viewing beam path and theOCT-scanning beam path pass through the ophthalmoscopic magnifier lensand a second position whereat the viewing beam path and the OCT-scanningbeam path do not pass through the ophthalmoscopic magnifier lens.

The ophthalmoscopic magnifier lens permits bundling the OCT-scanningbeam on the ocular fundus of the patient in order to scan the ocularfundus and to simultaneously make the fundus visible in the ocular viathe optical viewing beam paths of the surgical microscope.

According to another feature of the invention, the optical elementbetween the scan mirror unit and the microscope main objective isconfigured as a movable lens unit. In this way, different section planesof a human eye can be scanned with OCT-radiation.

According to another feature of the invention, this optical element isaccommodated in a lens exchange unit. In this way, a rapid-back andforth switching between different scanning planes for OCT-radiation ispossible in the object region.

According to another feature of the invention, the optical element isconfigured as a zoom system having variable focal length. In this way, acontinuous variation of section planes examined in a patient eye is madepossible with OCT-radiation.

According to another feature of the invention, means for adjusting thefocal length of the main objective are provided. In this way, differentplanes of an object region can be examined with the ophthalmic surgicalmicroscope without it being necessary to shift the surgical microscope.

According to another feature of the invention, the scan mirror unit forscanning the OCT-scanning beam has a first scanning mirror. Preferably,and additionally, a second scan mirror is provided. The first scanmirror can be moved about a first rotational axis and the second scanmirror can be moved about a second rotational axis. The first rotationalaxis and the second rotational axis are laterally offset at right anglesto each other. In this way, an object can be scanned with a rasterpattern running perpendicular to each other.

According to another feature of the invention, the OCT-system includes alight conductor which has a light exit section for the OCT-scanningbeam. Means are assigned to the light conductor for moving the same. Inthis way, the OCT-system can be adapted for the use of OCT-radiation ofdifferent wavelengths.

According to another feature of the invention, an ophthalmoscopicmagnifier lens is provided in the ophthalmic surgical microscope whichcan be pivoted into and out of the viewing beam path and theOCT-scanning beam path. Preferably, this ophthalmoscopic magnifier lensis combined with a reduction lens. The ophthalmoscopic magnifier lensand the reduction lens are arranged in an ophthalmic ancillary modulewhich can be pivoted into and out of the OCT-scanning beam path and theviewing beam path. In this way, the anterior section of the patient eyeas well as the ocular fundus can be examined with OCT-radiation with theophthalmic surgical microscope.

According to another feature of the invention, the OCT-system in theophthalmic surgical microscope is designed for making available a firstOCT-scanning light beam at a first wavelength and for making available asecond OCT-scanning light beam having a second wavelength different fromthe first wavelength. Preferably, a corresponding first OCT-system and acorresponding second OCT-system are provided which make available theOCT-scanning light beams of different wavelengths. In this way, bodytissue having different absorption characteristics for OCT-radiation canbe examined with good resolution.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawingswherein:

FIG. 1 is a schematic showing an ophthalmic surgical microscope havingan ophthalmic ancillary module and a first OCT-system;

FIG. 2 shows the ophthalmic surgical microscope of FIG. 1 having asecond OCT-system wherein the ophthalmic ancillary module is pivotedinto the viewing beam path of the ophthalmic surgical microscope;

FIG. 3 is a section view of the microscope main objective taken alongline III-III of FIG. 1;

FIG. 4 is a detail view of the ophthalmic surgical microscope havingfirst and second OCT-systems;

FIG. 5 shows the intensity distribution of the OCT-scanning light beamexiting from the light conductor of the OCT-system in the surgicalmicroscope;

FIG. 6 shows the intensity distribution of the OCT-scanning light beamin the OCT-scanning plane in the object region of the surgicalmicroscope; and,

FIGS. 7 and 8 show a modified embodiment for the OCT-system in thesurgical microscope.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The surgical microscope 100 in FIG. 1 has a microscope main objective101 defining an optical axis 102 as well as a focal plane 103.Stereoscopic viewing beam paths 105 of a binocular tube 106 pass throughthe microscope main objective 101.

The surgical microscope 100 has an illumination unit in the form of anillumination module 120 for illuminating the object region in the formof a patient eye 108. This illumination module 120 includes a firstlight conductor 121 which makes illuminating light 122 available from alight source (not shown). A displaceable field diaphragm 124 isilluminated by the illuminating light 122 exiting from the lightconductor 121. A path-folding mirror 123 is mounted on the side of themicroscope main objective 101 facing away from the object. Theilluminating light exiting from the light conductor 121 is directed viapath-folding mirror 123 through the microscope main objective 101 andinto the object region 108.

An ophthalmoscopic ancillary module 130 has a reducer lens 131 and anophthalmoscopic magnifier lens 132 which can be pivoted into and out ofthe stereoscopic viewing beam path 105 of the surgical microscope 100 incorrespondence to double arrows (133, 134). The ophthalmoscopicancillary module is assigned to the ophthalmic surgical microscope 100.

A first OCT-system 140 is provided in the ophthalmic surgical microscope100. The ophthalmic surgical microscope further contains a secondOCT-system 150 which is shown in FIG. 2. These OCT-systems permit therecordation of OCT-images.

The OCT-system 140 of FIG. 1 includes a unit 141 for generating andanalyzing an OCT-scanning beam 142. The unit 141 is integrated into thesurgical microscope 100. The unit 141 can, however, also be mountedoutside of the surgical microscope 100 in a corresponding stand console.The unit 141 is connected to a light conductor 143 which makes theOCT-scanning beam 142 available.

The OCT-scanning beam 142, which exits from the light conductor 143, isguided with a divergent beam path onto a first scan mirror 144 and asecond scan mirror 145 of an OCT-scan unit 146. From there, theOCT-scanning beam passes through an optic element in the form of aconverging lens 147 to thereafter pass through the microscope mainobjective 101. The OCT-scanning beam 142 is bundled in an OCT-scanningplane 160 in the anterior section of the patient eye 108.

The OCT-light, which is backscattered from the object region in the formof a patient eye 108 into the OCT-scanning beam path, arrives back inthe unit 141 via the microscope main objective 101, the converging lens147 and the OCT-scanning unit 146. In unit 141, the OCT-scanning light,which is backscattered from the object region, interferes with theOCT-radiation from a reference beam path. The interference signal isdetected by a detector and is evaluated by a computer unit which, fromthe signal, determines an optical path length difference between scattercenters for OCT-light in the object region and the path length of lightin the reference branch.

A displacing mechanism 148 is assigned to the converging lens 147 foradjusting the OCT-scanning plane 160. The converging lens 147 can bemoved by the displacing mechanism 148 in correspondence to the doublearrow 149.

The first OCT-system 140 operates at a wavelength of λ=1310 nm. Thesecond OCT-system in the ophthalmic surgical microscope 100 isconfigured to correspond to the first OCT-system 140 but has a workwavelength of λ=800 nm. It is understood that the OCT-systems can alsobe designed for other operating wavelengths. Operating wavelengths canbe realized in the range 600 nm<λ<1500 nm and are advantageous dependingupon application.

FIG. 2 shows the ophthalmic surgical microscope 100 of FIG. 1 with thesecond OCT-system 150. The second OCT-system 150 is configured andarranged in correspondence to the first OCT-system 140.

Identical component groups of the surgical microscope are provided inFIG. 2 with the same reference numerals.

The OCT-system 150 has a unit 151 for generating and analyzing anOCT-scanning beam 152 of the OCT-system 150. The OCT-system 150generates OCT-scanning radiation 152 at the exit end of the lightconductor 153. In the same manner as the OCT-scanning beam 142 ofOCT-system 140 of FIG. 1, this OCT-scanning beam 152 is guided via anOCT-scanning unit 156 having a first scan mirror 154 and a second scanmirror 155 via an optical element through the microscope main objective101. This optical element is configured as a converging lens 157.

FIG. 2 shows the ophthalmic surgical microscope 100 in an operating modewherein the reducer lens 131 and the ophthalmoscopic magnifier lens 132of the ophthalmic ancillary module 130 are pivoted into the viewing beampath 205 of the surgical microscope 100. This makes possible anexamination of the ocular fundus 190 of the patient eye 108 with theOCT-scanning light and with light which arrives from the ocular fundus190 back in the viewing beam paths of the surgical microscope.

The converging lens 157 bundles the OCT-scanning beam and directs thisbeam to the microscope main objective 101. The OCT-scanning beam reachesthe patient eye 108 via the microscope main objective 101, the reducerlens 131 and the ophthalmoscopic magnifier lens 132 and is bundled inthe OCT-scanning plane 170 at the ocular fundus 190 of patient eye 108.

The OCT-light, which is backscattered into the OCT-scanning beam pathfrom the object region in the form of a patient eye 108, is guided backinto the unit 151 for generating and analyzing an OCT-scanning beam. Thebackscattered OCT-light is guided into the unit 151 via the microscopemain objective 101, the converging lens 157 and the OCT-scanning unit156. In the unit 151, the OCT-scanning light, which is backscatteredfrom the object region, in turn interferes with OCT-radiation from areference beam path. As in the OCT-system 140, the interference signalis detected by a detector in the OCT-system 150 and is evaluated by acomputer unit which, from the signal, determines an optical path lengthdifference between scattering centers for OCT-light in the object regionand the path length of light in the reference branch.

A displacing mechanism 158 is assigned to the converging lens 157 whichcan be moved by the mechanism 158 in correspondence to the double arrow159. In this way, a focal plane can be adjusted also for theOCT-scanning beam from the OCT-system 150.

The optical path length of the OCT-scanning beam path in the operatingmode of the ophthalmic surgical microscope 100 shown in FIG. 2 is longerthan in the operating mode of FIG. 1. This requires an adaptation of theoptical path length in the reference beam path of the OCT-system 150.For this purpose, a coupling 180 of ophthalmoscopic magnifier lens 132and OCT-system 150 is provided which effects, with a pivoting of theophthalmoscopic magnifier lens 132 into the viewing beam path and theOCT-beam path, the optical path length of the reference beam path in theOCT-system to increase by a specific value. This value is preferablyheld to be adjustable. A fixed value advantageously orients itself tothe average length of the patient eye.

FIG. 3 is a section view taken along line III-III of FIG. 1. FIG. 3shows the course of the stereoscopic viewing beam paths (105, 205) ofthe surgical microscope 100 of FIG. 1. Two stereoscopic component beams(105, 205) pass through the microscope main objective 101. The opticalaxis 102 of the microscope main objective lies at the center 310thereof. The OCT-scanning beam 142 of the OCT-system 140 passes throughthe microscope main objective 101 in the region 301. The OCT-scanningbeam 152 of the OCT-system 150 of FIG. 2 passes through the microscopemain objective 101 in region 302 and the illuminating light 122 passesthrough the objective 101 in the region 303.

FIG. 4 shows the first OCT-system 140 and the second OCT-system 150 inthe surgical microscope 100 of FIGS. 1 and 2. The wavelength range ofthe OCT-scanning beams of the two OCT-systems (140, 150) is, however,different: the first OCT-system is based on an OCT-scanning beam havingthe wavelength λ₁=1310 nm. The second OCT-system 320 operates with anOCT-scanning beam having the wavelength λ₂=800 nm. The same referencenumerals used in FIGS. 1 and 2 to identify the component groups of theOCT-systems 140 and 150 are used in FIG. 4.

The first scan mirror (144, 154) and the second scan mirror (145, 155)of the OCT-systems (140, 150) are mounted so as to be rotationally movedby position drives (401,. 402, 403, 404) about two mutuallyperpendicularly extending axes (405, 406, 407, 408). This permits theOCT-scanning beams (142, 152) to scan over a plane independently of eachother.

The OCT-scanning beam 142 of the first OCT-system 140 is guided to themicroscope main objective 101 via the converging lens 147. TheOCT-scanning beam 152 of the second OCT-system 150 passes through themicroscope main objective 101 via the converging lens 157.

FIG. 5 shows a front portion of the light conductor 143 of FIG. 1 havingfront face 502. The light conductor 143 operates as a monomode fiber forlight of the wavelength λ₁=1310 nm. The diameter (d₁) of the fiber coreof the light conductor 143 satisfies the relationship:

${\frac{d_{1}}{2} < {2.4\frac{\lambda_{1}}{2\; \pi \; N\; A_{1}}}},$

wherein: NA₁ is the numerical aperture of the front face of the lightconductor. Preferably, the diameter (d₁) of the fiber core of the lightconductor 143 lies in the range of 5 μm<d₁<10 μm. In this parameterrange, the light conductor 143 conducts the light with a Gaussian-shapedwave mode. The OCT-scanning light beam 142 exits from the lightconductor 143 with an approximately Gaussian-shaped beam profile whichis characterized by a waist parameter W₁ and an aperture parameter θ₁wherein:

$\theta_{1} = \frac{\lambda_{1}}{\pi \; W_{1}}$

An aperture angle of θ₁≈0.0827 rad results thereby as an index for thebeam divergence for a fiber core diameter of d₁=10 μm and a wavelengthλ₁=1310 nm.

The front face 502 of the light conductor 143 is imaged into anOCT-scanning plane via the following: the scan mirrors 144 and 145 inthe surgical microscope 100 of FIG. 1; the converging lens 147; and, themicroscope main objective.

FIG. 6 shows the course of the intensity distribution of theOCT-scanning light beam 142 perpendicular to the OCT-scanning plane 170.In the OCT-scanning plane 170, the intensity distribution of theOCT-scanning radiation has a smallest constriction. The diameter of theOCT-scanning beam path increases outside of the OCT-scanning plane. TheOCT-scanning light beam 142 exits from the light conductor 143 of FIG. 5with an approximately Gaussian-shaped beam profile. For this reason, theconverging lens 147 and the microscope main objective 101 of thesurgical microscope 100 of FIG. 1 effect a so-called Gaussian bundle 600of the OCT-scanning light beam 142 for the OCT-scanning beam in theregion of the OCT-scanning plane 160. This Gaussian bundle 600 ischaracterized by the confocal parameter (z₁) as an index for thelongitudinal expansion of the constriction of the Gaussian bundle and bythe waist parameter W_(1,A) as an index for the diameter of the smallestconstriction 602 of the OCT-scanning light beam 142 in the OCT-scanninglight plane, that is, for the diameter of the constriction thereof. Thefollowing applies:

${z_{1} = {2\frac{W_{1,A}^{2}\pi}{\lambda_{1}}}},$

wherein: λ₁ is the wavelength of the OCT-scanning light beam. Thefollowing relationship applies between the waist parameter W_(1,A) ofthe Gaussian bundle 600 and the waist parameter W₁ of the scanning lightbeam 142 (FIG. 5) which exits from the light conductor 143:

W_(1,A)=β₁W₁,

wherein: β₁ is the magnification parameter or demagnification parameterof the above-mentioned geometric image of the exit end of lightconductor 143 of FIG. 1 in the OCT-scanning plane. The parameter β₁ iscoupled to the focal length f₁₄₇ of the converging lens 147 of FIG. 1and the focal length f₂ of the main objective via the followingrelationship:

$\frac{f_{2}}{f_{147}} = \beta_{1}$

The size of structures, which can be resolved with the OCT-scanninglight beam 142, is determined by the diameter of the beam 142 in theOCT-scanning plane 160, that is, by the waist parameter W₁. If, forexample, an application requires a lateral resolution of the OCT-systemin the surgical microscope of approximately 40 μm, then, according tothe Nyquist theorem, the cross section of the OCT-scanning light beam142 must amount to approximately 20 μm in the OCT-scanning plane. For agiven wavelength λ₁ for the OCT-scanning light beam 142 of FIG. 1, themagnification of the optical image in the OCT-beam path and the diameterof the fiber core in the light conductor 143 must be suitably selectedfor a desired resolution of the OCT-system 140.

The confocal parameter (z₁) as an index for the longitudinal expansionof the waist of the Gaussian bundle determines the axial depth of fieldfrom which backscattered light can be detected in the OCT-scanning beam142 of FIG. 1. The smaller the confocal parameter (z₁), the greater isthe loss of the OCT-system with respect to lateral resolution whenremoving an object from the OCT-scanning plane 160 with this objecthaving been scanned with the OCT-scanning beam. The reason for this isthat the location of the scatter centers can be localized only withinthe “funnel” defined by the waist parameter W₁ and the confocalparameter (z₁).

As the axial resolution of an OCT-system is delimited on the one hand bythe specific coherence length of the light of the light source utilizedin the OCT-system and, on the other hand, the lateral resolution of theOCT-system decreases when the depth index thereof exceeds the expansiongiven by the confocal parameter (z₁), the adjustment of the confocalparameter (z₁) to the specific coherence length of the light sourceutilized in the OCT-system is favorable.

For a specific wavelength λ₁ of the OCT-scanning light beam 142, thepossible lateral resolution of the OCT-system of FIG. 1 results becausethe wavelength λ₁ and confocal parameter (z₁) determine the waistparameter W_(1,A). The optical units in the OCT-scanning beam path ofFIG. 1 and the dimensioning of the fiber core of the light conductor 143are then to be selected so that the particular waist parameter results.

The converging lens 147 in the surgical microscope 100 is preferably soadjusted that the focal plane 170 of the microscope main objective 101for the visible spectral range and the OCT-scanning plane 160 of theOCT-system 140 are coincident. Then, the waist 502 (FIG. 5) of theOCT-scanning beam lies in the focal plane of the surgical microscope.

For the OCT-scanning beam 152 of the OCT-system 150 of FIG. 2, the lightconductor 153 functions as a monomode fiber for light of the wavelengthλ₂=800 nm. The diameter (d₂) of the fiber core of the light conductor153 therefore satisfies the relationship:

$\frac{d_{2}}{2} < {2.4\frac{\lambda_{2}}{2\; \pi \; N\; A_{2}}}$

wherein NA₂ is the numerical aperture of the front face of the lightconductor 153. The OCT-scanning light beam 152 exits from the lightconductor 153 with an approximately Gaussian-shaped beam profile whichis characterized by a waist W₂ and an aperture parameter θ₂ wherein:

$\theta_{2} = \frac{\lambda_{2}}{\pi \; W_{2}}$

For the waist parameter of the OCT-scanning beam 152 in the OCT-scanningplane 170, the following applies:

W_(2,A)=β₂W₂,

wherein β₂ is the demagnification parameter of the geometric image ofthe exit end of the light conductor 153 of FIG. 2 in the OCT-scanningplane 170.

The parameter β₂ is defined by the focal length of the converging lens157 of FIG. 2, the focal length of the microscope main objective 101 aswell as by the reducer lens 131, the ophthalmoscopic magnifier lens 132and the cornea and lens of the patient eye 108.

The converging lens 157 is preferably so adjusted that, when the opticalviewing beam images the ocular fundus 190 of the patient eye 108 throughthe microscope main objective 101, the OCT-scanning plane 170 for theOCT-system 150 in the surgical microscope 100 is coincident with theocular fundus 190.

Alternatively to the described design of the OCT-systems in the surgicalmicroscope, an offset of the OCT-scanning plane and focal plane can alsobe provided in the surgical microscope. Preferably, this offset is notgreater than the confocal parameter (z) of the OCT-scanning light beamin the region of the OCT-scanning plane.

In that the OCT-scanning plane is disposed further from the microscopemain objective 101 of FIG. 1 by the confocal parameter (z), the depthmeasurement index for the OCT-system can be maximized in the objectregion.

In FIG. 7, a modified embodiment for an OCT-system is shown which can beutilized in the ophthalmic surgical microscope 100 of FIGS. 1 and 2.

Corresponding to the OCT-system 140 of FIG. 1, the OCT-system 700includes a unit 701 for generating and analyzing an OCT-scanning beam702. The unit 701 is so designed that OCT-scanning beams havingdifferent wavelengths can be generated and evaluated. A controlapparatus 703 is provided for adjusting the wavelength of the OCT-system700.

The OCT-scanning beam 702 exits from a light conductor 704 which isconnected to the unit 701. The OCT-scanning beam 702 reaches two scanmirrors (705, 706) which are movable in such a manner by drives (notshown) that an object region 708 can be scanned in an OCT-scanning plane707.

For the adjustment of different OCT-scanning planes, on the one hand, amagnification exchanger 709 is provided as a lens exchange unit in theOCT-system 700 and this exchanger 709 holds converging lenses ofdifferent refractive power (710, 711). These converging lenses (710,711) can be pivoted into and out of the OCT-scanning beam path 702. Inaddition, a drive unit 712 is assigned to the light conductor 704 whichpermits the exit end 713 of the light conductor to be moved incorrespondence to the double arrow 714 in order to vary the position ofthe OCT-scanning plane 707 in the object region.

The OCT-scanning beam 707 reaches the OCT-scanning plane via theconverging lens 709 which bundles the scanning rays and conducts thesame to the microscope main objective of the corresponding surgicalmicroscope.

FIG. 8 shows a further embodiment of an OCT-system for an ophthalmicsurgical microscope. In the same manner as the OCT-system 700, theOCT-system here has a unit 801 for generating and analyzing anOCT-scanning beam 802 which exits from a light conductor 803. In theOCT-system 800, the OCT-scanning beam 802, which exits from the lightconductor exit end 804, is guided by a corresponding scanning mirrorsystem 805 through a lens unit 806 with adjustable refractive powerwhich acts as a zoom system. Accordingly, it is in turn possible to varythe position of the OCT-scanning plane 807 in an object region 808.

A further modified embodiment of the surgical microscope 100 shown inFIG. 1 contains a focusable microscope main objective having anadjustable focal length. This measure too makes it possible to shift anOCT-scanning plane and to change the geometric imaging of the lightconductor exit end in the OCT-scanning plane.

It is understood that the foregoing description is that of the preferredembodiments of the invention and that various changes and modificationsmay be made thereto without departing from the spirit and scope of theinvention as defined in the appended claims.

1. An ophthalmic surgical microscope defining a viewing beam path andcomprising: a microscope main objective mounted so as to permit saidviewing beam path to pass therethrough permitting examination of aregion of an object; an OCT-system for recording images of said objectregion; said OCT-system providing an OCT-scanning beam and including ascanning mirror device for scanning said OCT-scanning beam; and, anoptical unit mounted between said scanning mirror device and saidmicroscope main objective for bundling the OCT-scanning beam exitingfrom said scanning mirror device and guiding the bundled OCT-scanningbeam into a beam path passing through said microscope main objective tosaid object region.
 2. The ophthalmic surgical microscope of claim 1,wherein said optical unit is a movable lens assembly.
 3. The ophthalmicsurgical microscope of claim 1, further comprising a lens changing unitand said optical unit being mounted in said lens changing unit.
 4. Theophthalmic surgical microscope of claim 1, wherein said optical unit isa zoom assembly having a variable focal length.
 5. The ophthalmicsurgical microscope of claim 1, said surgical microscope furthercomprising a focal length changing unit for changing the focal length ofsaid microscope main objective.
 6. The ophthalmic surgical microscope ofclaim 1, wherein said scanning mirror device includes a first scanningmirror; and, a first device for rotating said first scanning mirrorabout a first rotational axis.
 7. The ophthalmic surgical microscope ofclaim 6, wherein said scanning mirror device comprises a second scanningmirror; and, a second device for rotating said second mirror about asecond rotational axis laterally offset at right angles to said firstrotational axis.
 8. The ophthalmic surgical microscope of claim l,wherein said OCT-system further comprises a light conductor having anend portion having a light exit end face for said OCT-scanning beam;and, means for moving said end portion.
 9. The ophthalmic surgicalmicroscope of claim 1, further comprising a reduction lens being movablymounted; said reduction lens being movable into a first position whereatsaid viewing beam path and said OCT-scanning beam path pass through saidreduction lens and into a second position whereat said viewing beam pathand said OCT-scanning beam path do not pass through said reduction lens.10. The ophthalmic surgical microscope of claim 1, further comprising anancillary module being movably mounted; said ancillary module having anoptical assembly including at least one of an ophthalmoscopic magnifierlens and a reduction lens; and, said ancillary module being movablebetween a first position whereat said viewing beam path and saidOCT-scanning beam path pass through said optical assembly and a secondposition whereat said viewing beam path and said OCT-scanning beam pathdo not pass through said optical assembly.
 11. The ophthalmic surgicalmicroscope of claim 1, wherein said OCT-system comprises generatingmeans for supplying said OCT-scanning beam at a first wavelength and ata second wavelength different from said first wavelength.
 12. Theophthalmic surgical microscope of claim 1, wherein said OCT-system is afirst OCT-system providing a first OCT-scanning beam and said surgicalmicroscope further comprises a second OCT-system providing a secondOCT-scanning beam; and, said first OCT-scanning beam has a firstwavelength and said second OCT-scanning beam has a second wavelengthdifferent from said first wavelength.
 13. An ophthalmic surgicalmicroscope defining a viewing beam path comprising: a microscope mainobjective mounted so as to permit said viewing beam path to passtherethrough permitting examination of a region of an object; anOCT-system for recording images of said object region; said OCT-systemproviding an OCT-scanning beam and including a scanning mirror devicefor scanning said OCT-scanning beam; an ophthalmoscopic magnifier lensbeing movably mounted; said ophthalmoscopic magnifier lens being movablebetween a first position whereat said viewing beam path and saidOCT-scanning beam path pass through said ophthalmoscopic magnifier lensand a second position whereat said viewing beam path and saidOCT-scanning beam path do not pass through said ophthalmoscopicmagnifier lens.
 14. The ophthalmic surgical microscope of claim 13,wherein said OCT-system defines a reference beam path; and, saidsurgical microscope further comprises a coupling device for increasingthe optical path length of said reference beam path by a given valuewhen moving said ophthalmoscopic magnifier lens into said firstposition.
 15. The ophthalmic surgical microscope of claim 13, furthercomprising a reduction lens being movably mounted; said reduction lensbeing movable into a first position whereat said viewing beam path andsaid OCT-scanning beam path pass through said reduction lens and into asecond position whereat said viewing beam path and said OCT-scanningbeam path do not pass through said reduction lens.
 16. The ophthalmicsurgical microscope of claim 13, further comprising an ancillary modulebeing movably mounted; said ancillary module having an optical assemblyincluding at least one of said ophthalmoscopic magnifier lens and areduction lens; and, said ancillary module being movable between a firstposition whereat said viewing beam path and said OCT-scanning beam pathpass through said optical assembly and a second position whereat saidviewing beam path and said OCT-scanning beam path do not pass throughsaid optical assembly.
 17. The ophthalmic surgical microscope of claim13, wherein said OCT-system comprises generating means for supplyingsaid OCT-scanning beam at a first wavelength and at a second wavelengthdifferent from said first wavelength.
 18. The ophthalmic surgicalmicroscope of claim 13, wherein said OCT-system is a first OCT-systemproviding a first OCT-scanning beam and said surgical microscope furthercomprises a second OCT-system providing a second OCT-scanning beam; and,said first OCT-scanning beam has a first wavelength and said secondOCT-scanning beam has a second wavelength different from said firstwavelength.
 19. The ophthalmic surgical microscope of claim 13, furthercomprising an optical unit mounted between said scanning mirror deviceand said microscope main objective for bundling the OCT-scanning beamexiting from said scanning mirror device and guiding the bundledOCT-scanning beam into a beam path passing through said microscope mainobjective to said object region.
 20. The ophthalmic surgical microscopeof claim 19, wherein said. optical unit is a movable lens assembly. 21.The ophthalmic surgical microscope of claim 19, further comprising alens changing unit and said optical unit being mounted in said lenschanging unit.
 22. The ophthalmic surgical microscope of claim 19,wherein said optical unit is a zoom assembly having a variable focallength.
 23. The ophthalmic surgical microscope of claim 19, saidsurgical microscope further comprising a focal length changing unit forchanging the focal length of said microscope main objective.
 24. Theophthalmic surgical microscope of claim 19, wherein said scanning mirrordevice includes a first scanning mirror; and, a first device forrotating said first scanning mirror about a first rotational axis. 25.The ophthalmic surgical microscope of claim 24, wherein said scanningmirror device comprises a second scanning mirror; and, a second devicefor rotating said second mirror about a second rotational axis laterallyoffset at right angles to said first rotational axis.
 26. The ophthalmicsurgical microscope of claim 19, wherein said OCT-system furthercomprises a light conductor having an end portion having a light exitend face for said OCT-scanning beam; and, means for moving said endportion.